The present invention relates to golf clubs and, more specifically, to golf clubs having reference marks thereon for various purposes.
It is generally recognized by golfers that putting is one of the most difficult skills to master in that it, unlike most other golf shots, requires not only appropriate skill in swinging the putter, but also requires the ability to anticipate the path a golf ball will take, after being struck, as it rolls across the undulating contour of the green. Since this undulating contour generally varies substantially from green to green, and from one point on a given green to another, the golfer is constantly faced with the problem of detecting or "reading" the particular contour of the green between the cup and the ball which is about to be putted, whereby the golfer can make appropriate adjustments in the force and direction of the putting stroke to compensate for the effect which the green contour will have on the path of the ball after it is struck. Accordingly, the ability of a golfer to accurately detect or "read" a given green contour will generally improve substantially the golfer's effectiveness in putting.
As is well known to engineers, architects and surveyors, a vertical reference line or "plumb" line is most helpful when viewing a landscape horizontally thereacross in enabling someone to accurately detect the contour of the landscape and to accurately assess the deviation thereof from horizontal. Thus, many golfers, realizing this, attempt to utilize one of their golf clubs, usually the putter, to strike a vertical plumb line with the club shaft thereof by dangling the club by its grip at arms's length for sighting past it across the green. However, since the club heads of virtually all golf clubs and putters manufactured and sold today are geometrically unsymmetrical and/or affixed to their club shafts in an offset manner, the weight of the club head of a conventional golf club is not evenly distributed with respect to its shaft, and therefore the golf club, when loosely dangled from the upper end thereof, will not assume a true vertical disposition. As a result, the dangling golf club will not present a consistent, vertical plumb line, and the vertical offset of the club shaft will be apparent from every perspective from which it is viewed by the golfer holding the club except the one perspective where, by change, the golfer happens to hold the golf club at the one position at which the vertical offset lies in a vertical plane that coincides with the golfer's line of sight. Because conventional golf clubs do not provide any reference indicator by which a golfer can determine when the golf club is being held at the aforesaid one position providing an effective plumb line, and because it is unlikely that a golfer will hold the golf club at such one position by chance, a golfer cannot rely upon the accuracy of the apparent plumb line presented by dangling a conventional golf club from its upper end or grip.
The subject of plumb lining as it relates to the art of putting a golf ball has been treated in several articles in golfing periodicals, one of which articles appears at pages 44-49 in the September, 1978, issue of Golf Digest and is entitled "Can plumb bobbing help you?" As is noted in the article, many professional golfers feel that plumb lining of putts is merely a psychological aid to golfers while others are convinced it is a worthless exercise. The author of the article attributes such attitudes to the fact that few, if any, golfers properly practice plumb lining, and therefore he endeavors to instruct golfers in the proper technique. Although it is correctly noted that it is vital that the club be held properly to establish a true vertical plumb line, the author's observation that the head of the putter must extend either directly toward or away from the golfer when plumb lining is somewhat incorrect in that it fails to consider fully the hereinabove-mentioned fact that many club heads are not geometrically symmetrical. Since each differently configured and constructed putter club head will have its own center of gravity different from that of other club heads, each type of putter or other club must be held for plumb lining in an orientation peculiarly unique to that particular type of putter and different from other putters in order for its club shaft to appear to strike a true vertical plumb line. In view of these facts, it is quite understandable why plumb lining is so widely practiced incorrectly and its effectiveness is doubted by so many golfers.
Various devices have been proposed for attachment to the shaft of a conventional golf putter for the purpose of providing the golfer with a horizontal reference line when the golfer orients the club shaft vertically. Examples of such devices are disclosed in U.S. Pat. No. 3,182,401 to W. E. Stevens and U.S. Pat. No. 3,186,092 to C. S. Bertas. Unfortunately, such devices have not been accepted well by golfers at least partially due to the fact that the accuracy of the horizontal line provided is dependent entirely upon the accuracy of the verticality of the shaft of the golf club with which they are used, which, as explained above, is seldom correctly accomplished by golfers. In recognition of the inherent difficulty in utilizing a conventional golf club to strike a plumb line with the shaft thereof, various golf putter modifications have been proposed to better enable a golfer to utilize the putter for plumb lining. Thus, in U.S. Pat. No. 3,242,582 to C. L. Garrett, the provision of a small, pendulum-type, plumb line indicator slidably disposed in a recess in the end of the gripping handle of a conventional golf putter is disclosed for enabling a golfer to accurately determine a plumb line by withdrawing the indicator from its recess and holding the putter by the indicator in the above-described plumb lining manner. In U.S. Pat. No. 4,114,886 to Koch, a golf putter is disclosed having a geometrically symmetrically shaped and weighted putter head and having a plumb bob contained within the putter handle so that, when the club is held by the plumb bob in plumb lining manner, the club shaft will strike a vertical plumb line regardless of the orientation of the club circumferentially around its shaft with respect to the golfer. Although putters modified according to these inventions may enable a golfer to accurately determine verticality with consistency, putters manufactured according to such inventions will necessarily be more expensive than a comparable conventional putter due to the provision of a special plumbing arrangement within its handle. Moreover, the necessarily unusual configuration of the club head of the latter-mentioned putter is greatly different from that of most putters and thereby necessarily limits the acceptability of the putter.
In contrast to the above devices and in recognition of the fact that the shaft of any golf club or putter will extend in an offset but generally vertical disposition unique to that club or putter when held in the above-described plumb lining manner so as to appear to strike a vertical plumb line when such vertical offset lies in a plane coinciding with the golfer's line of sight, the present invention provides a manner of marking a golf club at a particular location along the shaft thereof to identify the perspective from which the shaft must be viewed when held in plumb lining manner for it to present a vertical plumb line, which manner of marking may be utilized with any golf club or putter.